Core B: Clinical This Core evaluates and follows all participants entered into the studies of the program project. It uses established clinical and psychometric protocols (including Uniform Data Set assessments) at entry and annually thereafter to obtain clinical, neurological, and behavioral data to carefully characterize each participant, including dementia diagnosis and staging. Clinical Core data are used by all Cores and Projects to explore the correlates of very mild dementia of the Alzheimer type (DAT) in comparison with healthy brain aging. Core B: Clinical recruits and maintains an adequate sample size to supply needed participants for the projects. There is an increased need for nondemented participants as the program project explores AD changes in the brain prior to the occurrence of dementia (preclinical AD). The Core will refer participants to Core E: Imaging to obtain the Common Anatomic Protocol, assess participants in Project 1 (Preclinical AD predicts poststroke dementia) 1-year poststroke and annually thereafter, obtain blood from all participants for analysis in Project 2 (Antecedent biomarkers of AD in CSF and plasma) and Project 4 (Sequence variation in genes for biomarker proteins and age at onset of AD), and refer participants to Project 2 for CSF collection and to Project 3 (Markers for DAT: Control, variability, and personality) for study participation. Through its successful voluntary autopsy program the Core provides Core D: Neuropathology with autopsy material for neuropathologic diagnosis. Core B works closely with Core C: Biostatistics to ensure appropriate data management. The Core supports Core A: Administration in promoting scientific interactions among all investigators to accomplish the aims of the program project as a whole.